The double aortic arch is a form of vascular ring that constitutes
a class of congenital anomalies in which the trachea and oesophagus are
encircled by connected segments of the aortic arch and its branches.
Although it takes various forms, the common defining feature is that
both the left and right aortic arches are present. (1)

Case presentation

A 6-month-old infant presented with a longstanding persistent
cough, episodic spells of shortness of breath, gasping-like efforts
after feeding, and an unusual noise while breathing, and was reported to
have turned blue on two occasions after feeding. A chest X-ray showed
significant narrowing of the trachea 2 cm above the carina. An upper
gastro-intestinal study (Fig. 1) showed anterior bowing and extrinsic
compression of the posterior wall of the oesophagus at the mid-thoracic
level, and the trachea was narrowed and showed anterior bowing. The
differential diagnosis included an aberrant right subclavian artery, and
a double aortic arch was suspected. A thoracic computed tomography (CT)
angiogram (Fig. 2) confirmed the presence of a vascular ring created by
a double-sided aortic arch with compression of the trachea and
oesophagus.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

Oesophagography has a high sensitivity in detecting vascular
compression of the trachea and oesophagus, and is the investigation of
choice in some centres to screen for suspected vascular compression. (2)
In patients with a double aortic arch, bilateral indentation of the
oesophagus is observed on the anteroposterior view, with the right-sided
indentation superior to the left, and posterior indentation is observed
on the lateral view. For a more thorough diagnostic study, CT or
magnetic resonance imaging (MRI) should be performed. (3) Multi-slice CT
with 3-D reconstruction allows precise evaluation of any airway
compromise and a detailed assessment of the anatomy of the vascular
anomalies. (4) MRI is also well suited for imaging vascular structures
in the mediastinum without involving ionising radiation or the need for
intravenously administered contrast material, (5) which is a
consideration in young patients, where radiation exposure should be
avoided as far as possible. (6)

We thank Dr Jonathan Hack of Sunninghill Radiology, Johannesburg,
who produced and provided the above images.

Dr Seedat is a registrar in the Department of Radiology, University
of the Witwatersrand, Johannesburg. Professor Andronikou is affiliated
to the Department of Radiology, University of the Witwatersrand, and is
President of the College of Radiologists of South Africa. Professor Modi
was Head of the Department of Radiology, Chris Hani Baragwanath
Hospital, Johannesburg, at the time of writing and is affiliated to the
Department of Radiology, University of the Witwatersrand. Dr Lorgat is a
paediatrician in private practice at Lenmed Clinic, Johannesburg.